Telephone-receiver.



N. BALDWIN. TELEPHONE RECEIVER. APPLICATION FILED JAN. 29, 1908.

Patented Dec. 1, 1908.

UNTTED STATES PATENT OFFICE.

NA-,THnNIEL BALDWIN, OF HEBER, UTAH, ASSIGOR OF ONE-HALF TO-WILLIAM WITT, OF

HEBER, UTAH.

TELEPHONE-RECEIVER.

Specification of Letters Patent. Application filed January 29, 1908. Serial No. 413,226.

Patented Dec. 1, 1908.

To all wlwmit may concern:

Beit knownthatI, a citizen of the United States, residing at Heber city, in the county of Wasatch and State of Utah, have invented a new and useful Telephone-Receiver, of which the followlng is a specification. l

This invention has reference to improvements in telephone receivers, and its object 1s to provide a means whereby the magnetic fluxin the permanent magnets is'not affected by the change of polarity in the alternating opposing actions and therefore the -and be currentscoming over the line. By this means, slnce the telephone currents simply divert the greater part of the flux first vthrough one side of the pole pieces and then through the other, considerable loss of energy is' avoided from hysteresis and eddy currents 1n the permanent magnets'and in the armature.

In accordance with the present invention each pole of the permanent"magnet of the receiver isformed with a soft iron pole piece having two opposing legs each of which carries a suitably wound coil, and the several coils are so wound and connected up that the magnetic effect is produced first on one side of the armature, whether such armature be the diaphragm itself or be connected to 'the diaphragm, and then upon the other side of the armature.

Since the two legs of each pole piece strade die the armature, the latter is under balaned 1aagm is under little or no strain. This, together with the fact that the magnets do not necessarily act directly upon the diahragm, permits the use of a non-magnetic iaphragm such for instance as mica, and, therefore, the dia hragm may be made much lighter and more elicate and sensitive to the impulses coming over the line. Again, to produce the best results, the diaphragm may e .made comparatively thick in the center rogressively thinner toward the edges. f course the instrument, like any other magneto telephone, may be used as a,

transmitter, but because of the combined effect of the several ple pieces, the constancy of the flux through the magnets and armature, the elimination to a greater or less 1 extent of hysteresis and eddy currents, the

balanced armature and delicate diaphragm, there is a markedly greater part ofthe en.- ergy of the sound waves converted into al- NATHANIEL BALDWIN, l

lconning the gaskets ternating currents onthe line for the purpose of telephonie transmission.

In addition tothe above, the invention likewise comprises certain details of the construction which, together with the main parts of the invention, will be best understood by a consideration of the following detailed description taken in connection with the accompanying drawings forming a part of this specification, in which drawings- Figure 1 is a central section through the telephone" receiver. tion at right angles to that of Fig. 1. Fig. 3 is a bottom plan view of the receiver with a portion of the casing removed, and Fig. 4 is a detail artially diagrammatic view of a modified orm.

Referring tothe drawings, there is shown a rin 1 of any suitable material, which shoul be non-magnetic and may be either metal or other material, as desired. This ring may consist of brass or hard rubber or wood or whatever material may be chosen by the-manufacturer, except that the material must not be magnetic. This ring 1 is formed with two opposing ortions 2 3 so that the interior space of t e ring instead of being circular is substantially rectangular, as indicated at 4. One edge of the ring is formed with an annular recess 5 in which is seated two gaskets 6-6 which maybe of rubber or other suitable material, confining between theml a diaphragm 7 which may be of the ordinary circular type. This diaphragm, however, in the form shown in Figs. 1, 2 and 8, not being under the direct control of the pole pieces of the magnet, need not be of magnetic material but may be madeof mica or other non-magnetic material, and for the best results it is found that it is desirable to make the diaphragm thicker at its center than at its edges, and this diaphragm is so indicated in the drawings without, however, confining the invention to the use of such diaphragm. The, outer edge of thel rin 1 is formed with-screW-threads, as indicate at 8 for the rece tion of a suitable casing 9 hav'- ing one ven partially inclosed by a mouth piece 1() which also serves the purpose of 6 in their seat in the ring 1 and bringing such pressure to bear upon the gaskets `as to firmly clamp the diaphragm in place.

Secured to the under face of the ring 1, that is the face away from the mouth piece 2 is a similar secf -which in t 10, are two permanent magnets 11, 11, substantially semi-circular in sha e and secured to the ring 1 by screws 12. T e like poles of the magnets face each other and are s aced sufficiently to receive between them so t iron pole pieces which in turn may be secured to the ring 1 by screws 14. There should, however, be good magnetic contact between the polar faces of the magnets and the soft iron pole pieces 13. The polar designations of the ma ets 11 are indicated by the letters N and as usual.

Each soft iron pole piece 13 is extended toward the axis of themagnets, and beyond the inner eriphery of the magnets when assembled t ese pole pieces are formedwith two opposing legs 15, 16, shown in Fig. 1 as curved in arcs of a circle with their free ends closely approaching but still suiiiciently separated for a purpose which will presently appear. Instead of curving the legs 15 and 16 of the pole pieces, as shown in Fig. 1, these legs may be parallel for a distance, as indiv cated at 17 in Fig. 4, and'then be bent at an angle-to form ap roaching portions 18,-as also indicated in Fig. 4.

Each le 15 and 16 is inclosed in a coil 19 e structure shown in Fig. 4 may be woundupon a spool 20. The several coils which in the form shown in the drawings are four in number, are connected up in series and to the line, and-in order to provide for connecting the coils tol line the portion or i ledge 2 of the ring 1 has its upper face recessed, las indicated'at 21,'to receive` the heads of two screws 22 extending'xthrou h two perforations inthe ledge 2 andbelow t e same into the space between the inner faces ofthe magnets. Each screw 22 4is suitably insulated by an insulating sleeve 23 from the ring 1 when the samev is of metal, and is held 1n place by a nut 24 and also beyond the nut receives a bmdmg nut 25 so that the screw 22, with the binding post.A o Extending through the side wall of the casing v9-there ,is a perforation indicated at 26, and through the ring 1 is a corresponding perforation indicated at 27 matching the perforatlon 26, vand the perforation 27 terminut 25, constitutes in fact a nates ina recess 28 formed'on the underside v of the ledge 2. The perforations 26 and l27 permit the introduction of a'ilexible cord 29 of the double conductor 4and the terminals of these conductors =may be spread out and connected to the respective binding posts in the usual manner. -There is thus provided a means whereby allthe terminal connections are inclosed in the casing, and there are no exposed electrical connections in the structure.

Between the opposing ends of the 'leg's 15 and 16 of the soft iron pole pieces, there is located an armature 30 which may be in the form of a small rectangular plate, and

'while the legs r phone diaphragm is moved in the opposite through the center of this armature there extends a pin 31 which may be soldered or otherwise secured to the armature so'that the two parts are'in immovable relation one to the other. The upper end of the pin 31 is connected by a short link 32' extending through the center of the diaphragm and secured thereto by means of washers 33 and drops of solder or otherwise, as may be desired. The pin 31 and link 32 may alsobe connected by a drop of solder. The pin 31 extendsbelow the armature 30 and is there connected by solder or otherwise tothe free end of a leaf s ring 34, the other end of which is fast on the ower end of a bracket 35 firmlysecured to they under side ofthe ledge 3 of the rin 1. y

'lghe free ends of the legs 15 and 16 of each pole piece 13, being ofthe same polarity andl these pole pieces straddling the armature 30, there 1s exerted upon the latter a substantially equal magnetic pull on each side, and the armature having been once adjusted so as to'be centralized with relation to the free yends of the legs 15 and 16, exerts practically no pull upon the .diaphragm and its weight being sustained in greater art by the s ring 34, the diaphragm is un er practical y no strain.

In order that access may he had to the interior of the structure and'also that the internal parts of the structure may be protected, there is" threaded to` t over the vthreaded end 37 of the sidewall of the casing 9. The instrument is of suitable size to be readily grasped by the hand of the user and in order that it may be suitably su ported when not in use, there is rovided aanger in the form of an v eye 37 aving a threaded stem 38 passing through the side wall of the casin 9 and confined in place by nuts 39, 40. f en the instrument is not in usev it is hung pendently from any suitable su port-by means of the eye37, and the con ucting cord 29'is also then pendent from the casing, and this may be the condition of the cord when the instru-v ment is in use so that' the cord isnever subjected to bending strains, which may ultimately injure the insulation and even'cause the breaking of the cord. Su pose, now, that the instrument is in use an alternating slpeech currents are coming over .the line.

he winding is such Lthat with one impulse the legs 15 ofthe two pole ieces have their magnetism strengthened w le the magnetism in the legs 16 of both poles piecesis weakened. 'Theresult is that the armature i -1s drawn toward the free ends of the legs 15 and the ydiaphra m participates in this movement. When t e next impulse, s'a the o posite direction, is received by t -e coils, t e armature is drawn 'toward the legs 16 15 are weakened, and the telerovided a cap 36 internally I eddy currents is practically prevented.

. The diaphragm Jforming -nopart of thev magnetic circuit may be made of non-magnetic material, and being under no lateral strain may also be made thin and sensitive and so oer but little resistance to the action of the magnetic effects upon the armature.

In Fig. 4, there'is shown a further modification wherein a diaphragm is itself the armature ofthe polar extensions 15 and 16, and in4 this case the diaphragm, which as indicated at 41, is made either of magnetic material wholly or that portion which is within the magnetic field may be made of magnetic material. The soft iron pole pieces are in this case made of two parts 42 and 43 so that the coils may be readily wound upon the spools 20, and the magnets 11 may also be made of two parts in order to clamp the gaskets 6 irmly against the diaphragm 41.

While I have described the connections between the armature and pin 31 and between the latter and the diaphragm 7 and spring 34, as being made by drops of solder, other means may be employed for the same purpose, and the connection between the ink 32 and the Idiaphragm may be made by reducing the size of the pin 32 and passing it through the two washers 33 and then by upsetting or riveting its free end.

While the pole pieces are shown as semicircular with the two legs in one piece, it is to be understood that for convenience of wind ing and construction they may each be made of two pieces as in Fig. 4, while the parts are shaped as shown in Figs. 1, 2 and 3.

What is claimed is:-

1. A magneto telephone having a permanent magnet, an armature in operative relation thereto, means for causing both poles of the magnet to act on each side of the armature, and means for producing opposite effects in the same pole piece.

2. A magneto telephone having a permanent magnet with divided polar extremities, an armature in operative relation to each member of eacli polar extremity, and means for varying the magnetic effect of the polar extremities on opposite sides of the armature.

3. In a magneto telephone, a ermanent ma net, soft iron pole pieces eac provided Wit opposing legs or extensions, an armature-in operative relation to the legs or extensions, and coils a plied to said legs or extensions and couple for producing opposite effects in the same pole piece.

4. In a ma neto telephone, a permanent magnet forme of two parts having like polar ends adjacent one to another, soft iron pole pieces confined between said adjacent ends of the magnets and extending one toward the v other, said pole pieces each terminating in opposing legs or extensions having their ends in proximity, an armature between the proximate faces of the legs or extensions of the pole pieces, and coils upon said legs or extensions connected for producing opposite effects upon the legs of the same pole'pieces.

5. A magneto telephone comprlsing a permanent magnet, soft iron pole pieces havin opposing legs or extensions, coils upon sai legs or extensions connected for opposing ef- Itects upon the legs of the same pole ieces, an

armature in operative relation to t e proximate ends of the legs of each pole piece, a diaphragm, and-connections between the armature and diaphragm. .Y

6. A magneto tele hone com rising a permanent magnet, poie pieces therefor, each having legs or extensions with their ends in proximity, coils upon said legs or extensions connected for producing opposing eiects upon the legs of the same pole piece, an ar-v mature in operative relation to the proximate ends of the legs or extensions ofthe pole pieces, a diaphra m, connections between the diaphragm an armature, a spring member, and connections between the latter and the armature.

7. A magneto telephone comprising a suitable casing, a permanent magnet formed of two members having their like poles in proximity, soft iron pole pieces extending toward the center of the magnet and each provided with opposing legs or extensions w1th their free ends in proximity, coils upon said legs or extensions, a diaphragm mounted in the casing and under the influence of the magnetic effects of the legs or extensions of the pole pieces, binding posts within the casing interior to the magnet, and means for the introduction of a lexible conducting cord through the walls of the casing and to the binding posts therein.

In testimony that I claim the foregoing as my own, I have hereto aiiixed my signature in the presence of two witnesses.

- NATHANIEL BALDWIN. Witnesses: f

JAMES WITT, FRED SONDEREGGER. 

